Strange metal structure 'that defies rules of science' found in ancient ruins

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The mystery behind an "awe-inspiring" metal column that has baffled experts for over a century has finally been cracked.

And, despite being made of iron, it doesn't corrode.

This contradicts everything we know about the metal, which is notoriously prone to the elements – developing a reddish-brown iron oxide coating at the slightest sign of water.

?

Fair dinkum, neither hypothesis has come to fruition. Instead, the structure's power can be attributed to the ancient Indians' expertise.

Scientists thoroughly examined the pillar to determine the intricate chemical processes occurring beneath its dull grey exterior.

Yes, they revealed the secrets of how the marvel was created.

The towering column is approximately 7.3 metres (nearly 24 feet) high and 41.6cm (just over 16.4 inches) in diameter, narrowing to about 30.5cm (12 inches) at the top, where an ornamental feature is located.

reports.

In around 1333 AD, the famous Moroccan explorer Ibn Battista supposedly wrote: “In the middle of the [Delhi] mosque is the amazing column of which no one knows what metal it's made of.

“One of their learned bloke told me it's called 'Haft Jûsh', which means 'seven metals', and it's made up of those seven. A bit of this column, about the length of my finger, has been polished, and that polished bit gives off a ripper of a shine. Iron can't leave a mark on it.”

Several inscriptions have been engraved on its surface, with the oldest being a six-line verse – written in the ancient Indian language Brahmi – that names a king called Chandra.

Researchers reckon the poetic style and form of the Sanskrit text on this engraving point to it being chiselled during the rule of King Chandragupta II Vikramaditya, who was the ruler of the Gupta empire from around 375 to 415 AD.

The inscription describes the king as a devotee of Vishnu, and says he dedicated the pillar to the god on a hill called Viṣṇupada, which is literally "the hill of Vishnu's footprint".

The location of this hill is still up for argument, but it's generally believed to be situated among the Udayagiri cave temples in Madhya Pradesh.

What made the pillar so strong?

The experts at the University of Delhi said: “The pillar, famous for its top-notch craftsmanship, flawless finish and resistance to corrosion, is a notable landmark showcasing an undeniable record of ancient Indian metalworking and engineering expertise.”

The paper explains that ancient Indian metal smiths were able to purify their ironwork to a remarkable 98 per cent.

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The heat used in these processes wasn't hot enough to melt the metal completely, so it was extracted as a "soft spongy mass" which was then hammered into shape to form the desired objects, the researchers explain.

Batches of this porous iron were then laid out and repeatedly pounded to separate the molten slag (mineral impurities), shaping it into a series of "pancake" shapes.

"The hot iron pancakes were then stacked on top of each other, and both were joined together using hand-held hammers," they write.

A close-up examination of this forged iron structure showed an unusual combination of properties that made the metal highly resistant to corrosion.

Furthermore, the hammering didn't get rid of the slag evenly – it left a patchwork of tiny, phosphorus-rich bits scattered among the iron.

This set up a network of electrical conductors, resulting in a chain of chemical reactions, the researchers claim.

“The corrosion-resistant property of the Delhi Iron Pillar sample was largely due to its manufacturing process, which led to high slag inclusions being dispersed throughout the metal in three dimensions,” the study concludes.

The phosphorus in FePO4 (ferric phosphate) gets oxidised to phosphate which acts as an inhibitor and helps form protective oxide films to stop corrosion.

“The protective coating on the pillar reduces the corrosion rate from 0.395 mm to 0.040 mm per year.”

Fair dinkum, that's the answer all right. But wouldn't it have been ripper to have aliens behind it instead?

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